WASHINGTON  -  The Environmental Protection Agency on Friday justified blocking California and other states from regulating auto emissions by saying the pollution doesn't cause them unique problems.

In a 48-page document describing the reasoning behind its much-criticized decision, the EPA argues that California doesn't have the ``compelling and extraordinary conditions'' required for a waiver under the Clean Air Act, because the rest of the nation also suffers the effects of global warming.

EPA Administrator Stephen L. Johnson, who has faced lawsuits and angry denunciations since making the decision in December, told The Associated Press in a phone interview that legislative history shows California must have a unique problem in order to justify a federal waiver to implement a vehicle emissions law stricter than the federal government's.

``I'm not saying that California isn't experiencing problems as a result of global climate change. There are in fact other parts of the country that are actually worse,'' said Johnson.

Environmentalists and California officials disagree with Johnson's interpretation, contending that California has been granted Clean Air Act waivers in the past to deal with problems that are also happening elsewhere, such as diesel pollution.

Critics also contend that California does, in fact, have uniquely worse problems from global warming compared with other states, including wildfire risks, air pollution and water supply problems.

California's law would have forced automakers to cut greenhouse gas emissions by 30 percent in new cars and light trucks by 2016.

In denying the waiver request, Johnson argued that a nationwide approach would be better and he said it would be provided by a new law raising fuel economy standards. Automakers applauded Johnson's decision.

California officials argued that California's law would be stronger and act faster.

(AP)